1. Field of the Invention
This invention relates to a catalyzer type exhaust gas purification apparatus for use in a lean mixture combustion type internal combustion engine.
2. Description of the Prior Art
In prior art apparatus of this kind, a catalyzer or catalytic converter for exhaust gas purification is connected in an exhaust passage of a lean mixture combustion-type internal combustion engine. However, with this type of apparatus, when unburned components are increased in the exhaust gas during deceleration of the engine, a violent or rapid reaction takes place in the catalyzer and the catalyzer is liable to rise in temperature and exceed a critical temperature.
In the case of a lean mixture type internal combustion engine, a comparatively large amount of oxygen is always present in the exhaust gas so that when the unburned components are increased, the unburned components react violently or rapidly in the catalyzer in the presence of the oxygen. Thus, the catalyzer temperature is rapidly raised, which can result in damage.